This invention relates generally to circuits for processing video signals, and more particularly to a circuit capable of operating positively detection of the maximum (or minimum) value of a video signal from a video signal generating apparatus such as a television camera, and low-pass filtration of the video signal.
In general, there are circuits of a type in which a number of pores in a picture image of the sea bottom on the reproduced television picture picked up by television camera is counted in an electronic manner. In this circuit, upon counting, the video signals of the object picked up by the television camera, is subjected to conversion into binary-coded signals.
In the circuit known, heretofore, for converting and processing the video signal into the binary-coded signal, it is difficult to set a clipping level (or slicing level) of a clipper (or slicer), because the mean value of the signal fluctuates in accordance with information contents of the video signals. Therefore, there arises a difficulty in which the signal conversion and processing into binary-coded signal can not be carried out correctly and effectively.
Moreover, in the case of attempting to obtain picture screen of faded picture, it has been a practice to eliminate high-frequency components of the video signal by passing it through a low-pass filter. However, since the low-pass filter known, heretofore, is composed of a resistor and a capacitor, when square-wave signals are passed through this low-pass filter, for example, the rising characteristic and falling characteristic become out of symmetry, which leads to deterioration of picture quality of the television picture.